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Issue 11, 2017
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Unusual activation pathways of amines in the reactions with molybdenum pentachloride

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Abstract

The 1 : 1 molar reactions at room temperature of MoCl5 with aliphatic amines were investigated in dichloromethane. Pyrrolidine, diethylamine and dibenzylamine underwent dehydrogenative oxidation when allowed to react with MoCl5; the compounds [MoCl5{NCH(CH2)3}], 1, and [CH3CH[double bond, length as m-dash]NHEt][MoOCl4], 2, were isolated in moderate to low yields from MoCl5/pyrrolidine and MoCl5/NHEt2, respectively. The chloride–amide complex [MoCl4(NEt2)], 3, was afforded in 65% yield from MoCl5 and Et2NSiMe3. The interaction of MoCl5 with Me2NSiMe3 was accompanied by activation of the solvent, and the complexes [MoCl3(NMe2)(κ2-Me2NCH2NMe2)], 4a, and [MoCl3(NMe)(κ2-Me2NCH2NMe2)], 4b, co-crystallized from the reaction mixture. The reactions of MoCl5 with a series of primary amines afforded mixtures of products, and the Mo(VI) chloride imido complexes [MoCl4(NR)]2 (R = Cy, 5a; tBu, 5b) were isolated in ca. 40% yield from MoCl5/NH2R (R = Cy, tBu). C–H bond activation may be viable in the reactions of MoCl5 with tertiary amines: the compounds [(CH2Ph)2N[double bond, length as m-dash]CHPh]2[MoCl6]·CH2Cl2, 6, and [NHEt3]2[Mo2Cl10], 7, were obtained from MoCl5/tribenzylamine and MoCl5/triethylamine, respectively. Pyrrolidine and tribenzylamine underwent analogous activation pathways when allowed to react with [MoCl3{OCH(CF3)2}]2 in the place of MoCl5. The isolated metal products were characterized by analytical and spectroscopic techniques, in addition the structures of 1, 2, 4, 5a, 6·CH2Cl2 and 7 were ascertained by single crystal X-ray diffraction studies. The organic products were identified by NMR and GC-MS after hydrolysis of the reaction mixtures. DFT calculations were carried out in order to assist the IR assignments, and clarify structural and mechanistic aspects.

Graphical abstract: Unusual activation pathways of amines in the reactions with molybdenum pentachloride

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Publication details

The article was received on 19 Dec 2016, accepted on 02 May 2017 and first published on 08 May 2017


Article type: Paper
DOI: 10.1039/C6NJ03992H
Citation: New J. Chem., 2017,41, 4329-4340
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    Unusual activation pathways of amines in the reactions with molybdenum pentachloride

    N. Bartalucci, M. Bortoluzzi, F. Marchetti, G. Pampaloni, S. Schoch and S. Zacchini, New J. Chem., 2017, 41, 4329
    DOI: 10.1039/C6NJ03992H

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